The invention is directed to a circuit that prioritizes one or more of a plurality of input channels. In particular, the invention is directed to an automatic microphone mixer having adjustable priority.
Voice activated systems allow a plurality of talkers to converse over a corresponding number of input channels. When an individual is talking above a given threshold, the other channels are muted or blanked by a fixed amount. This allows the participants to direct their attention to and hear the particular talker while preventing or reducing feedback noise.
One significant shortcoming of such an approach is that the threshold level necessary to cause blanking or muting of the other talkers is often set so low that extraneous noise may cause the system mute out important discourse. In order to alleviate this problem, various gain sharing strategies have been developed in which the signal level in a particular channel is compared with the sum of all the channels to compute a gain sharing factor. The channel with the highest level input receives highest gain which is a proportional fraction of the total gain available. The advantage of such a system is that the total gain available to a particular location is not excessive.
Some known systems permit gain control to the audio circuit but this does not solve the priority problem, it simply allows one channel, when actuated, to have a higher volume. This can result in feedback problems which multiple channel systems seek to avoid.
It is therefore desirable to provide an automatic microphone mixer which allows priority without significant feedback.